An important part in electronic control of a vehicle is performed by a micro control unit (hereinafter, abbreviated as MCU). Therefore, failure of the MCU may cause results such as a driver and/or passenger fatalities and vehicle damage.
Therefore, it is very important to detect abnormality of MCU in order to increase the safety of the vehicle. There is a watchdog apparatus as an apparatus which detects the abnormality of the MCU.
The watchdog apparatus transmits and receives a watchdog signal and determines whether the received watchdog signal is received as predetermined data in a predetermined time.
Such a watchdog apparatus is disclosed in Korean Unexamined Patent Application Publication No. 10-2013-0009086 (published on Jan. 23, 2013, hereinafter, referred to as Patent Document 1). Patent Document 1 discloses a configuration in that after initializing a watchdog state, a state is transited between 000 and 111 and when a normal watchdog signal is input, the watchdog state forwardly moves by one step and when an abnormal watchdog signal is input, the watchdog state backwardly moves by two steps to increase reliability of the watchdog signal.
However, according to such a configuration, there is no way to check the stability of a computational operation of the MCU so that the configuration depends on a feedback signal for an external output value. According to this manner, a physical time in accordance with decision logic is wasted and thus delay is caused. Further, it is difficult to determine specific information on a failure area.